This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 5 |
| 3 | 21 |
| 4 | 45 |
| 5 | 285 |
| 6 | 765 |
| 7 | 27645 |
| 8 | 196605 |
| 9 | 41067645 |
| 10 | 72787965 |
| 11 | 250871805 |
| 12 | 4295098365 |
| 13 | 12884901885 |
| 14 | 23307153405 |
| 15 | 172130669565 |
| 16 | 1766029428523005 |
| 17 | 20978888016396285 |